Battery Powered Preamps

I have not heard Dodd, and am not suggesting that a minimalistic design can't sound great. Only that battery power restricts the designer in terms of number of tubes and type of tube used.

BBAM has only several active devices inside(low current op amps) which sound good on stock NiMH batteries, but much better on large SLA, both in terms of supple grainlessness across treble & mid and more dynamic scale and bass authority, owing to lower internal resistance and lower noise of SLA. Generally speaking the larger the SLA, the lower its impedance. In this case size matters in terms of transient response, independent of amp-hour capacity.

With lesser battery setups in my system I've heard a detailed & smooth treble & quiet black background, but pale/soft dynamic contrasts and lack of ultimate slam. If this is characteristic of Dodd, it could likely be improved with additional filtering capacitance and/or larger/faster batteries. Anybody at RMAF, please check out the new Roland battery pre and report as to whether strong or weak on these points. The Roland uses std D cell batteries.

I believe that a battery power supply done to the highest standards would be quite expensive in the marketplace.

A friend of mine incorporates heavy duty, fully-regulated rechargeable dual mono DC power supplies to power the preamp he manufactures and the DAC side of his cd player mods. (The batteries in the power supplies are hooked up to the A/C when the system is not in use, and then disconnected to play music.) I believe the batteries are 9 or 12 volts.

For best results, you need a separate power supply for each component. He sells these power supplies to friends for $1400 apiece. I can just imagine what the cost would be if both he and a dealer had to make a market profit on them. Moreover, the batteries are quite heavy.

I don't understand the electronics, so I can't explain what is involved in building the power supplies, or why they are so expensive. But I am sure there are good engineering reasons why a power supply containing regular batteries would not measure up.

I use a Battery powered TRL custom pre-amp. It is a very low gain design which suits my system very well and the sound is amazing.
I have owned many high-end tube and SS designs.
I have not owned one but have heard one extensively and the Reflection Audio OLM -1 battery pwered preamp is fantastic.
So yes, I think when well implemented and synergisitc with other components this is a great way to go.

The Dodd uses (2) 6dj8s and as previously mentioned, it only uses 1/2 of each tube (when they get old you switch tubes and the other half of the tube is used). I thought this was a pretty nifty feature for getting double the life from expensive NOS tubes, but maybe part of the decision was based on the battery supplies limitations in terms of driving tubes - don't know. Maybe a well implemented battery power supply is expensive, but nothing like the $10,000K + traditional preamps with robust powersupplies, often requiring a second chassis.

The RWA Isabella is an amazing tube preamp and runs completely on SLA battery power. I own it, along with the Signature 30.2 and the off the grid experience using these SLA batteries has very clear advantages to my ears.

6moons just released the review of the RWA Isabella. IMHO this review is spot on!

http://www.6moons.com/audioreviews/redwine10/isabella.html

Now I am playing with tube rolling using Amperex 7308s. Wow they are very sweet!!!

-Jeff